Editorial

Around Our Town...From the Game and Fish

G&F Biologist Search for Aquatic Nuisance Species

06/01/2005 - The biologists pulled the net through the shallow water of Harry Yesness Pond then stopped to inspect their catch. "We got some green sunfish," said Fisheries Biologist Scott Gangl. "We didn't put these fish here but they could have come here on their own through the Garden Creek water supply." Fish biologists from the Wyoming Game and Fish Department recently seined the pond in search of aquatic nuisance species, which are non-native species that can disrupt entire ecosystems by destroying habitat and altering food chains. They can be plants or animals, and are becoming a serious problem in Wyoming.

"We've seen a lot of instances where fish appear where they do not belong," said Regional Fisheries Biologist Al Conder. "People bring their own bait fish, or they release their aquarium fish into the waterways. Some of these fish survive and go on to cause serious problems in the ecosystems."

In the past, walleye have been found in Harry Yesness Pond, despite the fact that it is managed as a trout fishery. The City of Casper drained the pond, which removed the walleye, and the problem now seems to be under control. But other waters in the state have not been so fortunate.

"We've found red-rim melania in Midwest Reservoir," Conder said. Red-rim melania are a type of snail often sold in pet stores for aquariums. "The water source of that reservoir is from a warm-water well and we believe the warm temperature allows them to survive. We're monitoring the reservoir and waiting to see what will happen."

New Zealand mudsnails, a nuisance species that is rapidly spreading throughout the United States, were found in waters in Yellowstone National Park in recent years. The snails are thought to have come into the Great Lakes region in water released from a ship's ballast, or perhaps in the water of live game fish shipped from infested waters to western rivers in the United States. In the Madison River in Idaho, densities of New Zealand mudsnails have reached over 300,000 individuals per square meter. The snails compete for food and space occupied by native snail species. Trout and other game fish may also avoid them as prey, which reduces the food source available to these fish. Mudsnails reproduce asexually, with females born with developing embryos in their reproductive systems. "So it only takes one to reproduce into a new population," Conder said. New Zealand mudsnail and other species can be spread through something as simple as water in a live well or even muddy boots or equipment. Anglers are encouraged to thoroughly clean their fishing gear, waders and boats when they leave each body of water. A high-pressure rinse with warm water at a car wash is usually enough to remove any unwanted species that may be clinging to a boat, and washing waders and other gear by hand can also do the trick.

Game and Fish biologists said education is the key in preventing the spread of aquatic nuisance species. "Many of the introductions of these species occur accidentally because people simply do not know that what they are doing is wrong," said Aquatic Education Coordinator Janet Milek. "So we're working to make people aware of the problem."

However, Milek said there are also those people who intentionally release fish into waters where they do not belong. "These are people who don't like the way we are managing fisheries so they become bucket biologists and introduce a species of fish on their own. Maybe they would rather catch walleye than trout, so they dump walleye into a pond or lake and then we have a problem."

Biologists ask anglers to learn all they can about aquatic nuisance species and assist in preventing their spread in Wyoming. "Sometimes we can't do anything to control these species once they are established, so we have to work to prevent it," Conder said.

One way the Game and Fish Department works to do so is through fines. "Stocking fish illegally will get you a minimum fine of $210, with a maximum fine of $400 and/or six months in jail," said Game Warden Jason Sherwood. Persons responsible for illegally stocking fish could also be charged for any clean-up efforts the wildlife department must take to return a fishery to its former condition. "That could start at a couple thousand dollars," Sherwood said.

Anglers can also be fined for transporting live fish in their live wells. "Make certain you kill any fish that you catch before you leave the water," Sherwood said. The Game and Fish Department is always on the lookout for illegal stocking or transport of fish, whether intentional or not. "We do regular patrols and look for violators," he said. "And we rely a lot on word of mouth when someone else tells us that something like this is going on."

For more information on aquatic nuisance species, contact the Game and Fish Department at 473-3400 or online at http://gf.state.wy.us.